After obtaining written informed consent, patients will be randomly allocated (by closed envelope technique using computer generated random numbers) to one of the two groups- manual and automatic. The investigator will be present during the procedure for data collection purpose only and will not be involved in the conduct of anaesthesia. All patients will receive 5- 10mg oral diazepam as per institutional protocol the night before and on the morning of surgery as pre-medication. After shifting the patient to the operation table, patients will be started on normal saline 100 ml/hr (1-2 ml/kg/hr). Routine physiological monitoring will be commenced (pulse oximetry, electrocardiography, non-invasive blood pressure monitoring). BIS (Bispectral index)will be obtained by disposable sensors (Aspect medical system Inc. MA USA) attached to the forehead of the patient. Patients will receive 0.15 mg/kg of morphine sulphate before induction in aliquots of 3-5mg, during which indwelling arterial cannula, central venous line and pulmonary artery catheters (if deemed to be necessary) will be inserted.